Determine the open intervals on which the graph of y5x36x28x

Determine the open intervals on which the graph of y=-5x^3+6x^2+8x-8 is concave downward or concave upward.

y\'=-15x^2+12x+8=0 x=1.23,-0.43 y\'\'=-30x+12=0 x=0.4 For x<0.4,y\'\'>0 So concave upward for (-infty,0.4) For x>0.4,y\'\'<0 So concave downward for (0.4,infty)

$Determine the open intervals on which the graph of y=-5x^3+6x^2+8x-8 is concave downward or concave upward. Solution y\'=-15x^2+12x+8=0 x=1.23,-0.43 y\'\'=-30x+$